Hi Guys,
I'm a new member as of to-day! What a great resource the group is!
I've joined the thousands who can't be wrong and am building a Chip Amp using PCBs from Brian Bell. I didn't buy completed kits as I didn't see any point in having components that I could buy in the UK flown across the Atlantic. That decision is causing me some problems as I hadn't realised to what extent Brian had downsized the boards. I now can't find a source for quality resistors that are small eneough to fit the 5mm lead spacing. Could any members tell me what make of resistor Brian supplies in his kits and a UK or European supply source for them? I don't want to have to stand larger resistors up on end as it looks bad and results in longer leads than need be.
Apologies if this has been answered before but a search found nothing.
Thanks guys.
I'm a new member as of to-day! What a great resource the group is!
I've joined the thousands who can't be wrong and am building a Chip Amp using PCBs from Brian Bell. I didn't buy completed kits as I didn't see any point in having components that I could buy in the UK flown across the Atlantic. That decision is causing me some problems as I hadn't realised to what extent Brian had downsized the boards. I now can't find a source for quality resistors that are small eneough to fit the 5mm lead spacing. Could any members tell me what make of resistor Brian supplies in his kits and a UK or European supply source for them? I don't want to have to stand larger resistors up on end as it looks bad and results in longer leads than need be.
Apologies if this has been answered before but a search found nothing.
Thanks guys.
What if you contact Brian and nicely plead with him to send you the resistors? Postage for an envelope with them in it shouldn't be too pricey compared to the aggravation of hunting some down and still having to drive there or pay shipping locally.
You do realize that you don't have to use 0.5W resistors, yes? 1/4W would work fine too, except of course they can't replace the 2 x 2.7 Ohm on the output.
Hmm, it seems that a domain squatter has acquired (or I was redirected to it because the domain name expired), Brian's personal 'site with the amp gallery pictures so the wrong site loads at the URL briangt.com... I'd link it but there is no point since it doesn't go where it should.
You do realize that you don't have to use 0.5W resistors, yes? 1/4W would work fine too, except of course they can't replace the 2 x 2.7 Ohm on the output.
Hmm, it seems that a domain squatter has acquired (or I was redirected to it because the domain name expired), Brian's personal 'site with the amp gallery pictures so the wrong site loads at the URL briangt.com... I'd link it but there is no point since it doesn't go where it should.
Last edited:
Buy a development kit of quarter watt 1% resistors off ebay from a UK supplier. Stand them up on end, lots of miniaturized radios were built that way in the past, the extra bit of lead will make no difference at audio frequencies. Handsome is as handsome does.
you'll get 1000 delivered for £10, and you'll have the surplus to start off your junk-box (laboratory stores).
w
you'll get 1000 delivered for £10, and you'll have the surplus to start off your junk-box (laboratory stores).
w
Hello Levi,
I've just ordered a load of bits to make Brian's LM1875 kit, I got the boards from him and ordered the bits from Cricklewood Electronics Cricklewood Electronics - CCTV. CCTV Equipment. CCTV Systems. Digital CCTV Cameras good company because they do sell one offs of lots of things you don't have to buy 10 of everything, like some of the large companies.
e.g. They sell 1/4 Watt 1% resistors 10 for 50p.
Rgds - Jim
I've just ordered a load of bits to make Brian's LM1875 kit, I got the boards from him and ordered the bits from Cricklewood Electronics Cricklewood Electronics - CCTV. CCTV Equipment. CCTV Systems. Digital CCTV Cameras good company because they do sell one offs of lots of things you don't have to buy 10 of everything, like some of the large companies.
e.g. They sell 1/4 Watt 1% resistors 10 for 50p.
Rgds - Jim
Try:
RS Components | Electronic and Electrical Components free p+p and low cost orders accepted.
Farnell United Kingdom | world-leading distributor of electronic and maintenance, repair and operations products.
RS Components | Electronic and Electrical Components free p+p and low cost orders accepted.
Farnell United Kingdom | world-leading distributor of electronic and maintenance, repair and operations products.
Previously I was implying that since 1/4W resistors tend to be smaller than 1/2W, the OP might find some 1/4W short enough that they don't need to be tombstoned (up on end), or if they are a tight fit, a tiny bit of bending at the ends might still allow them to sit horizontal on the board even if a little nub of each lead remains.
I have also built things with vertical resistors and they sounded ok, but the theory and hype is that not doing it makes for a shorter signal path and less little *antennas* to pick up radio waves within the feedback loop, not only by decreasing the lead length but keeping it closer to the ground plane (assuming, since I don't remember for sure, that his kit PCB has a ground plane on the back...).
Last edited:
These will fit fine, I used them in my p2p LM3886 http://docs-asia.electrocomponents.com/webdocs/0382/0900766b80382001.pdf I got mine at RS australia, but it doesn't look like they have them at RS UK unfortunately.
however these (assuming that the values are the same as in my LM3886 which I based on Brians Schematic) might fit the bill
RS Components | Electronic and Electrical Components
Tony.
however these (assuming that the values are the same as in my LM3886 which I based on Brians Schematic) might fit the bill
RS Components | Electronic and Electrical Components
Tony.
^ while that is possible, the key word is "over" (bend). It's not hard to bend a resistor lead tightly without damaging it, but regardless random things can happen so personally I always order a few extras of any of the low cost parts I'll be using... at worst, I build up a little stockpile so I don't have to order as much or maybe not from as many places on the next project.
That's very interesting Simon thank you.
I will merely bend over the LM1875 leads and make little circles with my round nosed pliers on the resistor leads.
Ohh what about all the resistors on the boards? They are all bent over! Perhaps it would be better to remove them, put Veropins in the holes and solder the resistors to those.
Jim
I will merely bend over the LM1875 leads and make little circles with my round nosed pliers on the resistor leads.
Ohh what about all the resistors on the boards? They are all bent over! Perhaps it would be better to remove them, put Veropins in the holes and solder the resistors to those.
Jim
fwiw, I like the Vishay PR01 series (a 1 watter about the size of a 1/2 watt carbon composition, the Panasonic ERO series, and the Vishay CMF-55.
Mark Brasfield (formerly of National Semi) had the Panasonic ERO's in the BOM of his application note for the LM4702 amplifier. They are very small.
You can get a surface mount resistor kit from any number of distributors. These guys really help you out if you're using Vero prototyping board
Mark Brasfield (formerly of National Semi) had the Panasonic ERO's in the BOM of his application note for the LM4702 amplifier. They are very small.
You can get a surface mount resistor kit from any number of distributors. These guys really help you out if you're using Vero prototyping board
1/8W is also enough for the roles that these resistors have. A typical use for these metal films is just setting the chips gain etc. You don't need 3W carbon comps.
However, 1/4W is pretty much the standard general purpose resistor, and it is typically CHEAPER than a 1/8W, which might not seem to make sense...but 1/4Watters are made in much larger bulk, so therefore...lower price.
Also, I don't think bending the leads a little bit to get the resistor to fit (if it's too big) is going to make ANY noticeable sound quality difference. If any noise is created, it's nominal. Someone can fight me on that, but personally I wouldn't sweat it.
A 6mm 1/4W might be your best option. Try a Vishay CCF07 or something along those lines. Cheap and should be good enough for your purposes. They are 2% tolerance, which isn't as good as the fabled 1% or 0.1%, but again, these are things that you probably won't notice. I had a Logitech 2.1 system a few years ago that had tons of cheap carbon film resistors. Probably 5% tolerance....and the amp did sound quite good, regardless that it was using Cheng capacitors and the cheapest Mylar caps I have ever seen.
Don't get sucked in to using outrageously expensive components. The only thing I see worthwhile is electrolytic caps. Get good Japanese/American caps that you know won't leak. /tangent
You can also mounted them vertically and use a regular sized resistor. For my amps, I've used 1/4W Xicon metal film. Cheap and decent.
However, 1/4W is pretty much the standard general purpose resistor, and it is typically CHEAPER than a 1/8W, which might not seem to make sense...but 1/4Watters are made in much larger bulk, so therefore...lower price.
Also, I don't think bending the leads a little bit to get the resistor to fit (if it's too big) is going to make ANY noticeable sound quality difference. If any noise is created, it's nominal. Someone can fight me on that, but personally I wouldn't sweat it.
A 6mm 1/4W might be your best option. Try a Vishay CCF07 or something along those lines. Cheap and should be good enough for your purposes. They are 2% tolerance, which isn't as good as the fabled 1% or 0.1%, but again, these are things that you probably won't notice. I had a Logitech 2.1 system a few years ago that had tons of cheap carbon film resistors. Probably 5% tolerance....and the amp did sound quite good, regardless that it was using Cheng capacitors and the cheapest Mylar caps I have ever seen.
Don't get sucked in to using outrageously expensive components. The only thing I see worthwhile is electrolytic caps. Get good Japanese/American caps that you know won't leak. /tangent
You can also mounted them vertically and use a regular sized resistor. For my amps, I've used 1/4W Xicon metal film. Cheap and decent.
Thanks for all the responses. Although I accept that it is functionally OK to vertically mount the resistors I always hate doing it because I think that it is bad aesthetically. I have now found the "correct" size Phoenix/Vishay resistors at RS/Farnell/Digi-Key and will do battle with the minimum order number/minimum order value/high postage rates. Thanks again for all the suggestions.
Hi all, in the end I made my new amp with a pair of LM3876T's I bought on eBay and I used point to point wiring, it'll be much easier if I want to alter anything. I put up a thread about it here: http://www.diyaudio.com/forums/chip-amps/190770-point-point-chipamps-timber-cases.html
Jim
Jim
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.